(a) Field of the Invention:
The present invention relates to a lamp bulb assembly, and more particularly to an automotive lamp bulb assembly of which the bulb is replaceable.
(b) Related Art Statement:
A lamp bulb assembly with a lamp enclosure including a reflector has been proposed of which a plug body in which the lamp bulb is secured is removably attached to the reflector for replacement of the lamp bulb or for any other reason. A lamp bulb assembly of this kind is disclosed, for example, in the U.S. Pat. No. 4,500,946. As seen from this U.S. patent specification, the plug body in which the lamp bulb is secured has provided thereon a radially extending flange which is so formed as to be fixed, when axially forced by a locking collar, into an outer open end of a socket provided as extended axially at the back of the reflector. Three thread paths are formed circumferentially on the outer surface of the socket, and three notched passages are formed in the flange correspondingly to the thread paths. Further, there is formed on the front end of inner circumference of the locking collar a plurality of thread path following elements which can pass through the notched passages and the open ends of the thread paths when the plug is inserted into the socket. Also, there are provided on the rear end of the locking collar several compression tabs which press the flange to the socket when the locking collar is completely threaded. When attaching such plug into the socket, first the plug is inserted into the socket to a position where the flange touches the outer open end of the socket, and the notched passages are positioned so as to coincide with the thread path openings of the socket. Next, the locking collar is fitted onto the plug body, and the thread path following elements are positioned opposite to the notched passages and thread path openings. Thereafter, as the locking collar is turned clockwise while being axially pressed, the thread path following elements are engaged on the closed ends of the thread paths. As the result, the flange is rigidly pressed to the outer open end of the socket under the resilience of the compression tabs of the locking collar and the lamp bulb is retained in a pre- determined position with respect to the reflector.
However, such conventional lamp bulb assembly is disadvantageous in that the structure to attach the plug body to the socket is complicated and that the attaching procedure is tiresome because it is necessary to position the thread path openings of the socket, notched passages of the flange and the thread path following elements of the locking collar so as to be aligned with each other.